List out the characters or changes observed in secondary growth..
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=> Firstly, secondary growth is defined as the change or increase in the girth or width of the plant stem..
and this growth is possible only in case of dicots..
=>CHANGES::This involves mainly 3 vital functions..
▶ Initially, the cambial cells present in the tissue of stem, start converting to cambium, another meristems.
1. Formation of VASCULAR cambium=>
Since , the VASCULAR cambium present in between phloem and xylem,, is referred as intra fascicular cambium.After the joining of adjacent cells of medullary rays, leads to formation of complete cambial ring..such that it leads to the formation of inter fascicular cambium.
2.Activity of cambial ring.
=> After the cambial ring is formed, it becomes active and initiates the cut off new cells innerly and outerly.
=> The cells that cut towards out or towards pith are referred as secondary xylem..
=>The cells that cut off towards inner side are referred as phloem..
=> Inner cambium being more active than outer one.
=>As a result, the xylem cells get densely compact at the outer side, pushing the secondary phloem inwards,, however primary xylem remain either more or less intact.
=> At a same time cambium ring, forms a narrow band of parenchyma, that penetrate secondary xylem, and phloem with particular radial direction.These are the secondary medullary rays..
formation of secondary medullary rays means the termination of cambium activity..
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Hello !!
The answer is
⚫An aquatic plant is buoyed by the water in which it grows, and its structural needs are simple. Land plants, however, require a structural support system. During the course of evolution when plants developed the ability to synthesize lignin—the polysaccharide that gives rigidity to the cell walls of wood—large, erect bodies were achievable, and their possessors became highly successful in colonizing the land. In modern plants, lignified wood cells are the secondary xylem cells. Most of the primary tissues outside of the vascular cambium are destroyed by the sideways push of the new cells, and a new group of secondary tissues—the bark—replace them.
Vascular cambium
The vascular cambium lies between the primary xylem and phloem. It consists, accurately, of only one layer of cells, but the first cells it produces cannot be distinguished from cambial cells so the narrow area is sometimes referred to as the “cambium” or the “cambial zone.”
Wood: Secondary xylem
The structure of wood varies from species to species and between major groups. A common categorization separates the softwoods of gymnosperms from the hardwoods produced by angiosperms. (These are not very good descriptive terms because of the great variability in density among species in both groups, but the groups do differ in the kinds of cells in their wood.)
Hope it help u !!
The answer is
⚫An aquatic plant is buoyed by the water in which it grows, and its structural needs are simple. Land plants, however, require a structural support system. During the course of evolution when plants developed the ability to synthesize lignin—the polysaccharide that gives rigidity to the cell walls of wood—large, erect bodies were achievable, and their possessors became highly successful in colonizing the land. In modern plants, lignified wood cells are the secondary xylem cells. Most of the primary tissues outside of the vascular cambium are destroyed by the sideways push of the new cells, and a new group of secondary tissues—the bark—replace them.
Vascular cambium
The vascular cambium lies between the primary xylem and phloem. It consists, accurately, of only one layer of cells, but the first cells it produces cannot be distinguished from cambial cells so the narrow area is sometimes referred to as the “cambium” or the “cambial zone.”
Wood: Secondary xylem
The structure of wood varies from species to species and between major groups. A common categorization separates the softwoods of gymnosperms from the hardwoods produced by angiosperms. (These are not very good descriptive terms because of the great variability in density among species in both groups, but the groups do differ in the kinds of cells in their wood.)
Hope it help u !!
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